Radiotherapy; radiotherapy is a treatment modality that applies radiation to the location of tumor in order to destruct it or sometimes to eliminate adverse events caused by the tumor. Therefore, it is colloquially referred as “radiation therapy” or “X-ray therapy”. X-ray beams are used to prevent growth of cancerous cells or to kill them at the locus of treatment. Radiotherapy is a commonly used treatment modality of cancer. In fact, radiotherapy may be required at least once in 60-80 percent of cancer patients, after diagnosis is made.
How is the treatment method selected?
There are many factors that influence selection of treatment method. Most important ones are patient’s age, general health status, type of cancer, extent of metastasis and localization. Treatment-related decisions are made with multidisciplinary approach, a process that requires examination of the patient by many specialists from multiple relevant medical departments. A unique diagnostic and therapeutic plan is made and employed for each patient. Even if patients have same type of cancer, treatment should be planned according to conditions specific to the patient.
Who is included in the therapy team?
Radiation Oncologist They are responsible for determining dose of therapy delivered to which body region and how therapy will be modified according to response to radiotherapy and for evaluating side effects experience by physician.
Radiation physicist: This person is responsible for planning therapy and coordinating quality, safety and technical service and maintenance of devices. She/he works together with radiation oncologist in therapy planning and application.
Radiotherapy technicians: These people are trained to use radiotherapy devices. They do not stay with the patient in the same room during therapy; however, they are continuously in communication with the patient through a monitor found in the control room. They are responsible for positioning the patient correctly, operating the device and taking evaluation x-ray films during therapy.
Oncology nurse: S/he is a member of the team who stays most close to the patient, along with radiation oncologist, during treatment and follow-up of the patient. They act like a bridge between the physician and the patient to manage issues such as side effects and “Do’s and Don’ts”.
How is radiotherapy applied?
Radiotherapy is a matter of teamwork and requires a process. The patient needs to have a tomography scan for radiotherapy planning. While tomography is scanned, the patient is placed on a flat table and scanning is performed in a comfortable position, provided that the target area is included. On tomography scan, target organ and adjacent organs are identified in every slice in digital media. An accurate plan is made for each patient after radiotherapy dose, exposure of intact organs to how much dose and potential risks are calculated. Next, in the first day of radiotherapy, the patient is placed on the table at exactly the same position and radiotherapy plan is applied on the patient. At this stage, conformity of therapy plan is accurately verified on the patient in the digital media and each session is completed. Radiotherapy is applied for five days in weekdays and the therapy is skipped in weekends. It takes 10 to 15 minutes to verify therapy fields and 3 to 5 minutes to delivery radiation beams. Similar to roentgen scan, patient feels no pain while radiotherapy is applied; moreover, patient is monitored by technicians with camera at different angles.
RADIOTHERAPY DEVICE IN OUR HOSPITAL AND ITS SPECIFICATIONS
Linear Accelerator (LINAC) TRILOGY device, that includes 5 radiotherapy methods including CONFORMAL, IMRT, VMAT, SRS and IGRT, is used for diagnostic and therapeutic purposes.
3D CONFORMAL radiotherapy implies a therapy planning procedure where 3D tumor volume and critical organs are drawn using computed tomography images. In this modality, it is aimed to give the normal tissue the lowest possible dose while obtaining a dose that surrounds the tumor in a best possible way by giving a certain margin of target volume by multi-leaf collimators (Multi-leaf Collimator-MLC) of the linear accelerator.
With IMRT, intensity of X-ray beam is modulated. Thus, the intensity of the radiation in therapy area is adjusted and dose distribution is almost optimized. While high doses are applied to tumor, healthy tissues are conserved to the maximum extent.
VMAT (Volumetric Intensity Modulated Arc Therapy); it is a method of radiotherapy in which therapy is given in a very short period of time. In VMAT, duration of therapy is short relative to devices that do the same job. When radiation time of 2-3 minutes is added to imaging time that is less than 2 minutes, daily therapy is completed in 4 minutes totally in VMAT. While VMAT is performed, MLCs are moved according to positions of tumor and critical organs, and gantry and dose speeds are also changed during irradiation. Higher dose is more precisely targeted to the tumor using one or more than one arcs around the patient, while protection of sensitive organs is further maximized. With these features, VMAT can be defined as a simple, fast and effective radiotherapy method that hits the target precisely and correctly.
CRS SRS technology enables punctuate radiation. With this method, punctuate radiation can be given to very small tumors that measure several millimeters in size. Therefore, while the tumor is applied high radiation dose, surrounding normal tissue is given lower amount of radiation.
Image guided radiotherapy can be applied with IGRT. Image Guided Radio Therapy (IGRT) can be performed by using X-ray source on the remote control handles that are installed on the main body of our device, and reciprocal detector. With the help of IGRT feature, kV-kV image of the area of the patient, that will be treated, and Digitally Reconstructed Radiotherapy (DRR) images, those are taken by planning computer, can be evaluated in 2 dimensions before each therapy, and more importantly, Computed Tomography images can be obtained by turning robotic arms of the therapy device around the patients, and these images can be compared to reference images those are obtained by CT, that was scanned previously at simulation phase. Therefore, the patient can be included in therapy with same repeatability every day, and “set-up” uncertainties, those are originating from movements of organs, are minimized.